This is a co-pending application, related to Weisgerber, Motion Structure Production and Exhibition System, Application No. 07/228,495, filed Aug. 7, 1988. The parent application discloses a multi-component system for variably producing a high-impact, picture-dominance effect on motion picture audiences in a manner compatible with existing motion picture photographic and projection equipment, and in a configuration that can be installed in a conventional motion picture theater. The system disclosed in the parent application also produces the picture-dominance effect in a manner that permits switching the effect in or out of the system, alternating between conventional and high-impact experience as an aid to advancing the story line of the motion picture.
As part of the overall picture dominance system, the screen must be formatted and masked to appear to cover the entire front wall of the auditorium in which it is located. To achieve the necessary picture dominance effect, the screen must be side enough to cover a field of view at least 60.degree. wide and tall enough to present an elevational angle of at least 15.degree. above the horizontal, as seen by a member of the audience. For the picture dominance illusion to work, the viewers must not be able to see space around the screen or architectural features of the auditorium.
To provide the sharp framing that is needed for the overall effect, masks frame the screen on all four sides. Screen masking has long been known in the cinema art and was advanced considerably by the Vetter D-150 system (3,475,086). Vetter designed masking systems to frame a deeply-curved screen, producing a field of view 150.degree. wide, utilizing 70 mm film. The Vetter system yielded limited utility and versatility, however. His system was designed primarily for use with 70 mm film (aspect ratio 2.21:1). With movement of the upper and side screen masks, other aspect ratios could be accommodated, such as 1.85:1 (conventional 35 mm) or 2.39:1 (35 mm anamorphically compressed horizontally; "CinemaScope").
In practice, the actual D-150 installations placed air ducts immediately below the screen, resulting in high sight lines that reduced the effect of picture dominance. As practiced, Vetter's invention did not allow for the mechanical system that would move the lower mask to expose additional curved screen surface. In the system described in the parent application, 70 mm film is anamorphically compressed and expanded in the vertical direction by factors ranging from 1.25 to 1.5, yielding aspect ratios ranging from 1.77:1 to 1.48:1. In one embodiment of the system, anamorphic expansion by a factor of 1.33 yields an aspect ratio of 1.66:1. For image dominance to work, a screen wide enough to show conventional 70 mm films must be up to 50% taller than the Vetter screen to accommodate the extra vertical component caused by the anamorphic expansion. The original Vetter configuration would be inappropriate for the picture dominance mode described in the parent application, since it would be necessary to expose more viewing area at the bottom of the screen than Vetter had envisioned.
Methods for moving the top and side masks have been known for many years, and Vetter used these methods. The upper mask can be moved by a series of cables and pulleys, so that a motor would rotate a shaft in one direction to pull the mask up by "reeling in" the cables. Rotation in the other direction would produce momentary slack in the cables, allowing the weight of the mask to extend the cables to their full length as they were unwound. Side masks could be moved on reciprocating traverse rods, also controlled by a motor.
The system described in the parent application discloses the variation of screen size and aspect ratio between scenes or sequences within a single motion picture presentation. To accomplish this, it is necessary to move all four masks at the same time, so the picture will retain its horizontal and vertical symmetry as the picture-dominance mode is delivered or withdrawn. The effect requires exposure of extra screen surface along the lower edge, an idea not envisioned by Vetter. As practiced, Vetter's invention did not allow for the mechanical system that would move the lower mask to expose additional screen surface. In addition, the idea of moving all masks simultaneously to change frame size or aspect ratio during a picture did not occur to Vetter as useful (col. 3, lines 36-19):
Regardless of the photographic lens) which is used, the aspect ratio or screen size is rarely changed from scene to scene, or sequence to sequence, in projection, although it could be.
The ability to move all four masks is a necessary part of the new system which expands the creative control available to the filmmaker. While manual operation of the lower screen mask system described here is possible, automatic control allows movement during a single picture. This automatic activation of mask movement, as will be described, can also be used to facilitate motion picture theater operations.